APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

12 May 2003

Volume 82, Issue 19, pp. 3147-3362

Issue Cover Spotlight Figure

Appl. Phys. Lett. 82, 3266 (2003); http://dx.doi.org/10.1063/1.1572970 (3 pages)

Michael Mück, Christian Welzel, and John Clarke
Enlarge Image | Read More
Page 1 of 3 Pages Next Page | Jump to Page
back to top
RSS Feeds

Wide photonic band gaps at the visible in metallic nanowire arrays embedded in a dielectric matrix

N. Garcia, E. V. Ponizowskaya, Hao Zhu, John Q. Xiao, and A. Pons

Appl. Phys. Lett. 82, 3147 (2003); http://dx.doi.org/10.1063/1.1569656 (3 pages) | Cited 19 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present experimental verification of very wide band gaps at the visible by using a composite material consisting of an array of metallic nanowires embedded in a dielectric matrix. When the wavelength of the incident electromagnetic wave is long in such that the effective permittivity of the composite is negative, the electromagnetic waves will be reflected. At short wavelengths, the electromagnetic waves will go through the dielectric matrix. Therefore, the cutoff frequency is controlled by the average separation between metallic nanowires and their radii, allowing us to tune the band gap at will. These experimental results, in very good agreement with theoretical calculations, are at variant with many results that claim that the randomness will destroy the band gaps. In addition, the insulating nature of the composite minimizes the energy loss. Finally, it is easy and inexpensive to prepare samples. This work opens ground in the development of optical devices nanotechnology. © 2003 American Institute of Physics.
Show PACS
42.70.Qs Photonic bandgap materials
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
77.22.Ch Permittivity (dielectric function)

Horn resonator boosts miniature free-electron laser power

A. Bakhtyari and J. H. Brownell

Appl. Phys. Lett. 82, 3150 (2003); http://dx.doi.org/10.1063/1.1571959 (3 pages) | Cited 2 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The Dartmouth miniature grating-based free-electron laser is a benchtop device producing coherent, tunable terahertz radiation. Two resonator designs, the planar grating horn and the grating horn are described and their performance compared with the simple planar grating case. The grating horn increases output intensity by a factor of 100 without limiting the tuning range of the device. © 2003 American Institute of Physics.
Show PACS
41.60.Cr Free-electron lasers
42.79.Dj Gratings

Bragg-diffraction-type acousto-optic device using Pb(ZrTi)O3 film

Changho Lee, Sangho Kim, and Kwangsoo No

Appl. Phys. Lett. 82, 3153 (2003); http://dx.doi.org/10.1063/1.1571664 (3 pages) | Cited 3 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We fabricated a hybrid-type acousto-optic (AO) device [Pb(Zr,Ti)O3(PZT)/TiOx/SiO2/SiNx/SiO2/Si] and analyzed AO Bragg diffraction efficiency (ζ) to estimate the applicability of piezoelectric PZT to a Bragg-diffraction-type AO device. A surface acoustic wave (SAW) was generated on the PZT film, and an optical beam (He–Ne laser) was guided in the SiNx film. ζ was varied to 9% in the AO devices fabricated with various AO quality factors (Q) and film thicknesses of top SiO2 and PZT film, respectively. Using the results, we qualitatively analyzed the decay of SAW power to the film depth direction and AO figure of merit (M2 = 0.75×10−18 s3/g) of the SiNx film. © 2003 American Institute of Physics.
Show PACS
42.79.Jq Acousto-optical devices
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.65.Dq Acoustoelectric effects and surface acoustic waves (SAW) in piezoelectrics
42.79.Dj Gratings
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.Nk Insulators

Backflow in the relaxation of a hybrid aligned nematic cell

S. A. Jewell and J. R. Sambles

Appl. Phys. Lett. 82, 3156 (2003); http://dx.doi.org/10.1063/1.1573336 (3 pages) | Cited 7 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The optical convergent-beam technique has been used to measure the changing director profile in a 4.6 μm ZLI-2293 filled hybrid aligned nematic cell when a 7 Vrms ac voltage was removed. The relaxation process has been recorded in 0.3 ms time steps allowing the detailed director backflow occurring in the initial 9 ms of the reorientation process to be quantified. The measured tilt profiles over the 60 ms total relaxation period were compared to model tilt profiles produced using the Leslie–Eriksen–Parodi theory, and excellent agreement was found. Further analysis shows that the backflow is dominated by the viscosity coefficient η1 and the overall relaxation is governed by the coefficient γ1. © 2003 American Institute of Physics.
Show PACS
61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
42.70.Df Liquid crystals

Simultaneous generation of red, green, and blue quasi-continuous-wave coherent radiation based on multiple quasi-phase-matched interactions from a single, aperiodically-poled LiTaO3

Jun Liao, Jing-Liang He, Hui Liu, Hui-Tian Wang, S. N. Zhu, Y. Y. Zhu, and N. B. Ming

Appl. Phys. Lett. 82, 3159 (2003); http://dx.doi.org/10.1063/1.1570941 (3 pages) | Cited 26 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the experimental result of simultaneous generation of red, green, and blue (RGB) quasi-continuous-wave coherent radiation from a single, aperiodically poled LiTaO3 (APPLT), with a diode-pumped dual-wavelength Nd:YVO4 laser oscillating at 1064 and 1342 nm simultaneously. Red at 671 nm and blue at 447 nm were achieved by frequency doubling and tripling of a 1342-nm fundamental laser, respectively, and green at 532 nm was achieved by frequency doubling of a 1064-nm fundamental laser. The aperiodic structure provided three effective reciprocals to compensate the phase mismatches of the above three nonlinear processes at the same time. The result indicates that the APPLT may be employed to construct an all-solid-state RGB laser. © 2003 American Institute of Physics.
Show PACS
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation
42.79.Nv Optical frequency converters
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
42.70.Hj Laser materials
42.70.Mp Nonlinear optical crystals
42.79.Wc Optical coatings
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.By Design of specific laser systems

Linear and third-order nonlinear optical absorption of amorphous Ge nanoclusters embedded in Al2O3 matrix synthesized by electron-beam coevaporation

Q. Wan, C. L. Lin, N. L. Zhang, W. L. Liu, G. Yang, and T. H. Wang

Appl. Phys. Lett. 82, 3162 (2003); http://dx.doi.org/10.1063/1.1573332 (3 pages) | Cited 16 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Amorphous germanium (α-Ge) nanoclusters embedded in Al2O3 matrix are synthesized on fused-quartz glass substrate at room temperature by vacuum electron-beam coevaporation. Linear optical transmittance measurements reveal an indirect optical absorption edge with a blueshift as large as 1.6 eV due to the quantum confinement effects. The Z-scan method is used to study the third-order nonlinear absorption process of the synthesized samples, which clearly show a two-photon nonlinear process. Results also suggest that Ge nanocluster density or size is of great influence to the value of nonlinear absorption coefficient β. © 2003 American Institute of Physics.
Show PACS
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.65.-k Nonlinear optics
78.66.Jg Amorphous semiconductors; glasses
78.66.Db Elemental semiconductors and insulators
81.05.Gc Amorphous semiconductors
61.46.-w Structure of nanoscale materials
81.07.Wx Nanopowders
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Far-infrared (λ ≃ 87 μm) bound-to-continuum quantum-cascade lasers operating up to 90 K

Giacomo Scalari, Lassaad Ajili, Jérôme Faist, Harvey Beere, Edmund Linfield, David Ritchie, and Giles Davies

Appl. Phys. Lett. 82, 3165 (2003); http://dx.doi.org/10.1063/1.1571653 (3 pages) | Cited 97 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report terahertz frequency (3.5 THz, λ ≃ 87 μm) emission from quantum-cascade lasers employing a bound-to-continuum transition in the active region. The maximum operating temperature is in excess of 90 K. Peak powers of 20 mW at 20 K and 10 mW at 77 K are achieved. The same devices show continuous-wave operation up to 55 K with measured optical powers of 15 mW at 10 K. © 2003 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.21.Fg Quantum wells

Prism grating using polymer stabilized nematic liquid crystal

Hongwen Ren, Yun-Hsing Fan, and Shin-Tson Wu

Appl. Phys. Lett. 82, 3168 (2003); http://dx.doi.org/10.1063/1.1573366 (3 pages) | Cited 24 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A prism grating using polymer stabilized liquid crystal was fabricated and its diffraction characteristics evaluated. Such a prism grating exhibits not only a periodic grating structure but also a prism-like gradient refractive index within each grating period. As a result, the diffraction behavior is asymmetric. The first order exhibits high diffraction efficiency while the zeroth order has a high extinguishing ratio. The potential application as a beam deflector is emphasized. © 2003 American Institute of Physics.
Show PACS
42.79.Dj Gratings
42.70.Df Liquid crystals
42.79.Bh Lenses, prisms and mirrors
42.79.Ry Gradient-index (GRIN) devices
42.79.Fm Reflectors, beam splitters, and deflectors
42.79.Kr Display devices, liquid-crystal devices

Fluidic adaptive lens with high focal length tunability

De-Ying Zhang, Victor Lien, Yevgeny Berdichevsky, Jaehyuck Choi, and Yu-Hwa Lo

Appl. Phys. Lett. 82, 3171 (2003); http://dx.doi.org/10.1063/1.1573337 (2 pages) | Cited 89 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Fluidic adaptive lenses with an adjustable focal length over a wide range were demonstrated in this letter. The focal length adjustment was achieved by changing the shape of the fluidic lens without any mechanical moving parts. The shortest focal length demonstrated in such devices is 41 mm, which corresponds to a large numerical aperture of 0.24 and a small F number of 2.05. The highest resolution measured using a positive standard is 25.39 lp/mm in this fluidic adaptive lens. © 2003 American Institute of Physics.
Show PACS
42.79.Bh Lenses, prisms and mirrors
47.85.Np Fluidics
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

High refractive-index microspheres of optical cavity structure

Yusuke Arai, Tetsuji Yano, and Shuichi Shibata

Appl. Phys. Lett. 82, 3173 (2003); http://dx.doi.org/10.1063/1.1573331 (3 pages) | Cited 8 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Microspheres of refractive index of nD>2 have been investigated. The organic-inorganic hybrid microspheres of refractive index nD = 1.70–1.72 were prepared at room temperature by the vibrating orifice technique using titanium alkoxide and silane coupling reagents as starting materials. Subsequently heating the microspheres at 400–450 °C resulted in increasing their refractive indices to nD = 2.10–2.25 with keeping good spherical shape. Rhodamine 6G-doped microspheres of nD = 1.72 were also prepared at room temperature and the lasing from them was performed by pumping by second-harmonic pulses of Q-switched Nd–yttritium–aluminum–garnet laser. © 2003 American Institute of Physics.
Show PACS
42.55.Sa Microcavity and microdisk lasers
42.55.Mv Dye lasers
42.60.By Design of specific laser systems
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Electro-optic control of the superprism effect in photonic crystals

David Scrymgeour, Natalia Malkova, Sungwon Kim, and Venkatraman Gopalan

Appl. Phys. Lett. 82, 3176 (2003); http://dx.doi.org/10.1063/1.1574402 (3 pages) | Cited 26 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have designed a two-dimensional photonic crystal in electro-optic materials that can actively control the superprism effect. By applying an electric field to the photonic crystal, the electro-optic effect will change the dielectric constant of the material, which modifies both the band structure and the dispersion surfaces. In the proposed structures, we show that electric fields of up to 6 V/μm in (Pb0.09La0.91)(Zr0.65Ti0.35)O3-based photonic crystals can deflect light up to 49°. This device concept can be used for a class of optical modulation devices that can provide a local control of dispersion surfaces within a photonic crystal. © 2003 American Institute of Physics.
Show PACS
42.70.Qs Photonic bandgap materials
78.20.Jq Electro-optical effects
77.22.Ch Permittivity (dielectric function)

Picosecond sampling with fiber-illuminated ErAs:GaAs photoconductive switches in a strong magnetic field and a cryogenic environment

M. Griebel, J. H. Smet, J. Kuhl, K. von Klitzing, D. C. Driscoll, C. Kadow, and A. C. Gossard

Appl. Phys. Lett. 82, 3179 (2003); http://dx.doi.org/10.1063/1.1573367 (3 pages) | Cited 2 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A sampling setup for a cryogenic environment has been developed using fiber-illuminated photoconductive switches fabricated from a material composed of equidistant layers of self-assembled ErAs nanoislands in a GaAs matrix. The setup includes dispersion compensation of the fibers and exhibits a time resolution better than 2.2 ps, which is insensitive to temperature and applied magnetic field and limited only by the properties of the coplanar waveguide circuitry. In cryogenic photocurrent autocorrelation measurements on single switches, a resolution exceeding 850 fs could be achieved. © 2003 American Institute of Physics.
Show PACS
85.60.-q Optoelectronic devices
85.70.Sq Magnetooptical devices
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Polarization-controlled, single-transverse-mode, photonic-crystal, vertical-cavity, surface-emitting lasers

Dae-Sung Song, Yong-Jae Lee, Han-Woo Choi, and Yong-Hee Lee

Appl. Phys. Lett. 82, 3182 (2003); http://dx.doi.org/10.1063/1.1574398 (3 pages) | Cited 19 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We developed a polarization-controlled, single-transverse-mode, photonic-crystal, vertical-cavity, surface-emitting laser (PC-VCSEL) by introducing elliptical air holes in the top mirror. The polarization-controlled PC-VCSELs show polarization extinction ratios of over 29 dB. The origin of the polarization stability is explained by the asymmetric polarization mode profile and the asymmetric current injection profile. © 2003 American Institute of Physics.
Show PACS
42.55.Tv Photonic crystal lasers and coherent effects
42.55.Px Semiconductor lasers; laser diodes
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.Fc Modulation, tuning, and mode locking
42.60.By Design of specific laser systems
42.70.Qs Photonic bandgap materials

Multispectral long-wavelength quantum-well infrared photodetectors

P. Mitra, F. C. Case, J. H. McCurdy, S. A. Zaidel, and L. T. Claiborne

Appl. Phys. Lett. 82, 3185 (2003); http://dx.doi.org/10.1063/1.1573354 (3 pages) | Cited 3 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Multispectral detector arrays for application in the 8–11 μm spectral band have been fabricated from GaAs/AlGaAs multiple quantum-well (MQW) materials. For efficient narrow-band coupling of the infrared radiation, three-dimensional diffractive resonant optical cavities are patterned into the MQW material. The peak wavelengths of the multispectral quantum-well infrared photodetectors are tuned by controlling the dimensions of the resonant structure. The full width at half maximum of the spectral response is as narrow as 0.7 μm. As many as 24 different detector designs were implemented on a single array. The spectrally tuned detectors exhibit peak responsivities as high as 2.6 A/W and quantum efficiency as high as 57%. Total conversion efficiency is as high as 35%. The background limited peak detectivity measured at 9.0 μm and 55 K with a 295 K background and f/2.5 is ≥ 1×1011 cm Hz0.5/W. © 2003 American Institute of Physics.
Show PACS
85.60.Gz Photodetectors (including infrared and CCD detectors)
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
back to top
RSS Feeds

Proton Moiré fringes for diagnosing electromagnetic fields in opaque materials and plasmas

A. J. Mackinnon, P. K. Patel, D. W. Price, D. Hicks, L. Romagnani, and M. Borghesi

Appl. Phys. Lett. 82, 3188 (2003); http://dx.doi.org/10.1063/1.1569416 (3 pages) | Cited 10 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High contrast proton moiré fringes have been obtained in a laser-produced proton beam. Moiré fringes with modulation of 20%–30% were observed in protons with energies in the range of 4–7 MeV. Monte Carlo simulations with simple test fields showed that shifts in the moiré fringes can be used to give quantitative information on the strength of transient electromagnetic fields inside plasmas and materials that are opaque to conventional probing methods. © 2003 American Institute of Physics.
Show PACS
52.70.Nc Particle measurements
52.25.-b Plasma properties
52.65.Pp Monte Carlo methods
41.20.-q Applied classical electromagnetism
41.75.Ak Positive-ion beams

Formation of large-volume, high-pressure plasmas in microhollow cathode discharges

Hae Il Park, Tae Il Lee, Ki Wan Park, Hong Koo Baik, Se-Jong Lee, and Kie Moon Song

Appl. Phys. Lett. 82, 3191 (2003); http://dx.doi.org/10.1063/1.1573359 (3 pages) | Cited 15 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed two electrode configurations that employ one primary supply circuit with a variable resistor for large-volume, high-pressure glow discharges without glow-to-arc transitions, and have investigated their electrical and the photoimages in microhollow cathode sustained discharges. The applied voltage and the discharge current between electrodes were controlled by changing the resistance of a variable resistor, which could replace the secondary supply circuit in microhollow cathode sustained discharges for the formation of secondary discharge. The electrical and the optical measurements showed that the discharge passed through three distinct stages: no discharges, microhollow cathode discharges, and microhollow cathode sustained discharges. Compared with the two-supply circuit system that has a primary and a secondary supply circuit, this electrode configuration is very simple and inexpensive process in generating large-volume plasmas at high pressures. © 2003 American Institute of Physics.
Show PACS
52.80.Hc Glow; corona
52.50.-b Plasma production and heating
52.70.Ds Electric and magnetic measurements
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
back to top
RSS Feeds

InAs/GaAs(001) quantum dots close to thermodynamic equilibrium

G. Costantini, C. Manzano, R. Songmuang, O. G. Schmidt, and K. Kern

Appl. Phys. Lett. 82, 3194 (2003); http://dx.doi.org/10.1063/1.1572534 (3 pages) | Cited 29 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
InAs/GaAs(001) quantum dots are grown at high temperature and extremely low flux and analyzed by in situ scanning tunneling microscopy. A bimodal distribution of dots is observed, composed of “small” and “large” islands. While the former show a broad distribution of sizes and shapes, the latter appear to be highly uniform and have a truncated pyramid shape with irregular octagonal base. (110) and (111) facets are identified and atomically resolved showing (1×1) and (2×2) surface reconstructions, respectively. The shape of the large quantum dots is in excellent agreement with recent theoretical predictions, proving that the chosen deposition conditions are close to thermodynamic equilibrium. © 2003 American Institute of Physics.
Show PACS
68.65.Hb Quantum dots (patterned in quantum wells)
68.60.Dv Thermal stability; thermal effects
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)

Intensity and spatial modulation of spontaneous emission in GaAs by field aperture selecting transport

Thomas D. Boone, Hironori Tsukamoto, and Jerry M. Woodall

Appl. Phys. Lett. 82, 3197 (2003); http://dx.doi.org/10.1063/1.1572467 (3 pages) | Cited 4 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A potential technique for modulating the light emission resulting from excess minority carrier recombination in a semiconductor device is introduced. This process utilizes an electric field to transport a packet of minority carriers past an optical output aperture defined on the surface of the semiconductor. A short burst of light is allowed to escape through the surface of the device as the packet drifts past the opening in the aperture. To first order, the temporal length of the optical pulse will be a function of the width of the excess minority carrier packet, the width of the aperture, and the drift velocity of the excess minority carriers. In p-type gallium arsenide, geometric scales of 5 μm should make possible pulse widths near 100 ps. Initial experimental results are presented confirming the spatial displacement and the attenuation of the external luminescence intensity as a function of applied bias voltage. © 2003 American Institute of Physics.
Show PACS
78.55.Cr III-V semiconductors
78.20.Jq Electro-optical effects
78.47.-p Spectroscopy of solid state dynamics

Dynamic modeling and scaling of nanostructure formation in the lithographically induced self-assembly and self-construction

Lin Wu and Stephen Y. Chou

Appl. Phys. Lett. 82, 3200 (2003); http://dx.doi.org/10.1063/1.1572963 (3 pages) | Cited 25 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We numerically studied the dynamical formation process and the scaling of the nanostructures in the lithographically induced self-assembly and self-construction of thin polymer films. Our studies show that the period of the self-assembled pillars depends on the ratio between the surface tension force and the electrostatic force. The viscosity of the polymer has no effect on the final pillar shape. When the feature width of the mold is comparable to or smaller than the most unstable disturbance wavelength of the system, the initially self-assembled pillars will merge to form a self-constructed mesa. © 2003 American Institute of Physics.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

Parametric modulation mechanism of surface acoustic wave on a partially closed crack

J.-Y. Kim, V. A. Yakovlev, and S. I. Rokhlin

Appl. Phys. Lett. 82, 3203 (2003); http://dx.doi.org/10.1063/1.1572552 (3 pages) | Cited 4 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Low-frequency parametric modulation of a pulsed surface acoustic wave by a partially closed fatigue crack is described. The crack is initiated in the plastic-yielding zone induced by a surface cavity and clamped due to the constraint of the surrounding elastic medium. Small periodic loading, superimposed on a static crack opening load, changes periodically the crack closure state and produces a nonlinear modulation of the reflected ultrasonic pulses. We describe quantitative experimental and modeling results relating the reflected modulation spectrum to crack length, closure, and modulation load. Surface acoustic wave measurements, which were performed in situ during a fatigue test, show that the modulation response varies significantly depending on the ratio of the fatigue crack length to the size of the plastic-yielding zone. © 2003 American Institute of Physics.
Show PACS
68.35.Iv Acoustical properties
62.20.M- Structural failure of materials
68.35.Gy Mechanical properties; surface strains
81.40.Lm Deformation, plasticity, and creep

A high-temperature shape-memory alloy Ni54Mn25Ga21

Huibin Xu, Yunqing Ma, and Chengbao Jiang

Appl. Phys. Lett. 82, 3206 (2003); http://dx.doi.org/10.1063/1.1572540 (3 pages) | Cited 41 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A high-temperature shape-memory alloy, Ni54Mn25Ga21, was developed with a shape-memory effect of 6.1% and a martensitic transformation temperature higher than 250 °C for single crystals. The measured compressive strength and strain were 845 MPa and 20.5%, respectively, with a compressive axis along the growth direction of the rods at room temperature. One thousand thermal cycles were performed on the Ni54Mn25Ga21 without obvious changes of the martensitic structure, transformation behavior, and shape-memory effect, indicating an excellent thermal stability for the present alloy. © 2003 American Institute of Physics.
Show PACS
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
64.70.K- Solid-solid transitions
81.30.Kf Martensitic transformations

Reduced critical thickness for relaxing heteroepitaxial films on compliant substrates

G. Kästner and U. Gösele

Appl. Phys. Lett. 82, 3209 (2003); http://dx.doi.org/10.1063/1.1573355 (3 pages) | Cited 5 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is argued that heteroepitaxial thin films (layers) grown on a compliant substrate are not able to relax their strain elastically by large-area slip across a “weak” layer. Instead, the Matthews model of plastic relaxation is modified by supposing that the interfacial misfit dislocations relax their strain field or even disappear into the weak layer. Consequently, the moving film-threading dislocations experience a reduced drag force. Therefore, the critical film thickness is lowered, in contrast to the enhanced thickness predicted by current theories. A quantitative estimate is given which depends on the nature of the weak layer. Implications include a larger free slip path and potentially a lower density of film-threading dislocations. © 2003 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties
61.72.Bb Theories and models of crystal defects
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
62.20.D- Elasticity

High-quality InAsyP1−y step-graded buffer by molecular-beam epitaxy

M. K. Hudait, Y. Lin, D. M. Wilt, J. S. Speck, C. A. Tivarus, E. R. Heller, J. P. Pelz, and S. A. Ringel

Appl. Phys. Lett. 82, 3212 (2003); http://dx.doi.org/10.1063/1.1572476 (3 pages) | Cited 15 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
Relaxed, high-quality, compositionally step-graded InAsyP1−y layers with an As composition of y = 0.4, corresponding to a lattice mismatch of ∼1.3% were grown on InP substrates using solid-source molecular-beam epitaxy. Each layer was found to be nearly fully relaxed observed by triple axis x-ray diffraction, and plan-view transmission electron microscopy revealed an average threading dislocations of 4×106 cm−2 within the InAs0.4P0.6 cap layer. Extremely ordered crosshatch morphology was observed with very low surface roughness (3.16 nm) compared to cation-based In0.7Al0.3As/InxAl1−xAs/InP graded buffers (10.53 nm) with similar mismatch and span of lattice constants on InP. The results show that InAsyP1−y graded buffers on InP are promising candidates as virtual substrates for infrared and high-speed metamorphic III–V devices. © 2003 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.60.Bs Mechanical and acoustical properties
68.37.Lp Transmission electron microscopy (TEM)
61.72.Lk Linear defects: dislocations, disclinations
68.35.B- Structure of clean surfaces (and surface reconstruction)

Structure and phase stability of the CdTiO3–PbTiO3 system

D. Y. Suárez-Sandoval and P. K. Davies

Appl. Phys. Lett. 82, 3215 (2003); http://dx.doi.org/10.1063/1.1573362 (3 pages) | Cited 10 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The formation of solid solutions in the CdTiO3–PbTiO3 system has been examined using x-ray diffraction (XRD) and differential scanning calorimetry. The XRD data showed two solid-solution ranges for the (Pb1−xCdx)TiO3 system at 1170 °C; orthorhombic on the cadmium-rich side and tetragonal on the lead-rich side, separated by a two-phase region for 0.08<x<0.85. Despite the limited range of solubility the tetragonal (Pb1−xCdx)TiO3 solid solutions show a >10% increase in the c/a ratio, demonstrating that the role of Cd in this structure is quite unique. The enthalpy of the tetragonal-to-cubic phase transformation also increases with increasing Cd substitution, although the temperature of the transition is ∼20° lower than that found in pure PbTiO3. © 2003 American Institute of Physics.
Show PACS
64.70.K- Solid-solid transitions
61.66.Fn Inorganic compounds
81.30.Dz Phase diagrams of other materials
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
65.40.G- Other thermodynamical quantities

Vibrational study of tris-(8-hydroxyquinoline) aluminum/LiF/Al interfaces

P. He, S. D. Wang, S. T. Lee, and L. S. Hung

Appl. Phys. Lett. 82, 3218 (2003); http://dx.doi.org/10.1063/1.1573353 (3 pages) | Cited 9 times

Online Publication Date: 6 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Interface studies of tris-(8-hydroxyquinoline) aluminum (Alq3)/LiF/Al were carried out with high-resolution electron-energy-loss spectroscopy. With LiF on Alq3 or Al on LiF, no significant changes in intensity were observed for the loss peak related to the Li–F stretch mode. However, the deposition of less than one monolayer of Al on Alq3/LiF resulted in a strong attenuation of the LiF-loss peak, providing a direct evidence of LiF dissociation in the coexistence of Alq3 and Al with LiF. On the other hand, the LiF-loss peak remained almost unchanged when Al was deposited on poly (9,9-dioctyl-fluorene)/LiF. © 2003 American Institute of Physics.
Show PACS
68.35.Ja Surface and interface dynamics and vibrations
79.20.Uv Electron energy loss spectroscopy
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
Page 1 of 3 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close